The lawyer for a homeless man accused of pushing an American student into the Tiber River in Rome says surveillance footage shows the teen tried to swim a few strokes after falling in but was carried off by rapids and quickly disappeared.

Attorney Michele Vincelli, who is defending Italian suspect Massimo Galioto, said Thursday the dynamics of the incident are clear on the video but that it's still unclear who was responsible for the death of 19-year-old Beau Solomon of Spring Green, Wisconsin.

While Galioto was on the Tiber riverbank along with Solomon early Friday, at least three other people were there as well, Vincelli told reporters outside the Rome jailhouse after a judge confirmed Galioto's arrest.

"My client declares absolutely that he did not give the push," he said. The lawyer said Galioti invoked his right not to respond to investigators' questions.

Galioto was detained Tuesday on suspicion of aggravated homicide, a day after Solomon's body was pulled from the river downstream. Solomon was reported by another student to have been last seen at a bar early Friday, just hours after arriving in Rome for a summer study program at John Cabot University.

"It is a given that the boy was robbed and probably brought down onto the riverbank of the Tiber with the presumed thieves, but then they go away and then the next episode starts, during which there are various people who argue with the boy," Vincelli said.

Galioto's companion, Alessia Pennachioli, who lives with him in a makeshift Rome encampment under one of the Tiber's bridges, said Solomon "accidentally fell into the river" after he and Galioto scuffled. She said Solomon was drunk, and had been accompanied down the stairs to the riverbank by two North Africans who had robbed him.

"The victim had the bad luck to fall in the most unlucky spot in the whole river because just a bit further down there are the rapids," Vincelli told reporters. "You can see he tried to swim, but then he was pushed over the rapids, where there are also rocks that come out of the river."

The video, from police surveillance cameras on the other side of the river, is in the hands of Italian prosecutors, he added.

An autopsy showed that Solomon was alive when he fell in the water, Italian news reports said.

Investigators are also looking into Solomon's credit card, which was used at a Milan store on Saturday, a day after he died.

At Rome's City Hall, a minute of silence was observed in Solomon's honor during a ceremony Thursday afternoon to mark the inaugural assembly for the municipal government, after last month's election of a new mayor, Virginia Raggi, and city council members.